This invention relates to structure of a hose joint for connecting a hose to a fluid apparatus such as a piping, pump, valve, etc. for preventing damage by radiant heat to the hose from a radiant heat source located in the neighborhood of the hose joint.
In most places for taking out fluid pressure with a hose from a fluid apparatus, a metallic hose joint, with one end being fixedly connected to the fluid apparatus and the other end being inserted into the hose, is usually utilized. The hose in such places is usually made of an organic elastic material such as synthetic rubber or the like, so it is liable to deteriorate when it is subjected to direct heat radiation from a radiant heat source in the neighborhood thereof. When the radiant heat source is an exhaust manifold and the hose joint is connected to a vacuum pump located in the vicinity of the exhaust manifold, for example in a vehicle, a hose for taking out negative pressure from the vacuum pump often deteriorates to become fragile or easily breakable. It may cause paralysis of a device or apparatus utilizing negative pressure, such as a brake booster, which will possibly lead to a grave accident.
Against such a problem the idea of isolating the hose from the exhaust manifold, a radiant heat source, by means of elongating the hose joint has been proposed. However, the idea is still problematical, because the hose joint is liable to become weak or susceptible to engine vibration and to make the space of the engine room even narrower. Another idea is employment of a heat-resisting hose. It remarkably raises the cost of the hose, perhaps doubling, still leaving a problem whether the temperature to which the hose is resistant is sufficient or not.